Trends and correlation between antibiotic usage and resistance pattern among hospitalized patients at university hospitals in Korea, 2004 to 2012 A nationwide multicenter study

The aim of this study was to evaluate the changing pattern of antibiotic usage and antimicrobial resistance of bacterial pathogens among hospitalized patients in Korea. We simultaneously investigated the correlation between antimicrobial resistance and antibiotic consumption. Data on total antibiotic prescriptions, patient days, and antimicrobial sensitivity tests among inpatients from 6 university hospitals in Korea in 2004, 2008, and 2012 were collected. The consumption of each antibiotic class was converted to defined daily dose/1000 patient-days by using the anatomical therapeutic chemical classification system by the World Health Organization. We defined third generation cephalosporins (3rd CEPs), fourth-generation cephalosporins, beta-lactam/beta-lactamase inhibitors, and fluoroquinolones (FQs) as broad-spectrum antibiotics and carbapenems, tigecycline, glycopeptides, oxazolidinone, and polymyxin as antibiotics against multidrug-resistant (MDR) pathogens. A 15.1% decrease in total antibiotic consumption was observed in 2012 compared to that observed in 2004. In contrast, a 10.2% and 70.7% increase in broad-spectrum antibiotics and antibiotics against MDR pathogens were observed, respectively, in the same period. The resistance rate of Escherichia coli to 3rd CEPs (17.6% in 2004, 21.7% in 2008, and 33.8% in 2012, P<.001) and ciprofloxacin (37.5% in 2004, 38.7% in 2008, and 46.6% in 2012, P=.001) demonstrated a significantly increasing trend. Similarly, the resistance rate of Klebsiella pneumoniae to 3rd CEPs (34.3% in 2004, 33.7% in 2008, and 44.5% in 2012, P<.001) gradually increased. Resistance of Acinetobacter baumanii and Pseudomonas aeruginosa to imipenem significantly increased throughout the study period (A baumanii: 8.9% in 2004, 10.8% in 2008, and 65.3% in 2012, P<.001; P aeruginosa: 25.1% in 2004, 31.5% in 2008, and 29.7% in 2008, P=.050). The consumption of carbapenems and FQs demonstrated significant positive correlation for resistance of E coli or K pneumoniae to 3rd CEPs as well as E col; or K pneumoniae to ciprofloxacin. Increasing resistance of A baumanii to ciprofloxacin was significantly correlated with increasing consumption of FQs; increasing resistance of A baumanii to imipenem was significantly correlated with increasing consumption of carbapenems. In conclusion, overall antimicrobial resistance increased and consumption of broad-spectrum antibiotics and antibiotics against MDR pathogens subsequently increased in Korean hospitals.